Storage devices such as disk drives and other nonvolatile memory devices generally do not read or write data as quickly as other devices in a computer system. To smooth out the transfer of data to and from storage devices, a cache memory may be used. The cache memory will generally comprise volatile memory that operates more quickly than the storage device.
However, there are limitations in the use of cache memory for a storage device. Data stored in the cache memory that is intended for the storage device will be lost if a power failure results in loss of power to the cache memory or the storage device. For this reason, there are practical restrictions on the size and operation of a cache memory for a computer hard disk or similar memory device. The amount of write data that is stored in a cache memory may be limited to the amount of data a computer operating system is willing to lose in the event of a catastrophic power failure.